(function() {

var initPhotoSwipeFromDOM = function(gallerySelector) {

    var parseThumbnailElements = function(el) {
        var thumbElements = el.childNodes,
            numNodes = thumbElements.length,
            items = [],
            el,
            childElements,
            thumbnailEl,
            size,
            item;

        for(var i = 0; i < numNodes; i++) {
            el = thumbElements[i];

            // include only element nodes 
            if(el.nodeType !== 1) {
              continue;
            }

            childElements = el.children;

            size = el.getAttribute('data-size').split('x');

            // create slide object
            item = {
                src: el.getAttribute('href'),
                w: parseInt(size[0], 10),
                h: parseInt(size[1], 10),
                author: el.getAttribute('data-author')
            };

            item.el = el; // save link to element for getThumbBoundsFn

            if(childElements.length > 0) {
              item.msrc = childElements[0].getAttribute('src'); // thumbnail url
              if(childElements.length > 1) {
                  item.title = childElements[1].innerHTML; // caption (contents of figure)
              }
            }


            var mediumSrc = el.getAttribute('data-med');
            if(mediumSrc) {
                size = el.getAttribute('data-med-size').split('x');
                // "medium-sized" image
                item.m = {
                    src: mediumSrc,
                    w: parseInt(size[0], 10),
                    h: parseInt(size[1], 10)
                };
            }
            // original image
            item.o = {
                src: item.src,
                w: item.w,
                h: item.h
            };

            items.push(item);
        }

        return items;
    };

    // find nearest parent element
    var closest = function closest(el, fn) {
        return el && ( fn(el) ? el : closest(el.parentNode, fn) );
    };

    var onThumbnailsClick = function(e) {
        e = e || window.event;
        e.preventDefault ? e.preventDefault() : e.returnValue = false;

        var eTarget = e.target || e.srcElement;

        var clickedListItem = closest(eTarget, function(el) {
            return el.tagName === 'A';
        });

        if(!clickedListItem) {
            return;
        }

        var clickedGallery = clickedListItem.parentNode;

        var childNodes = clickedListItem.parentNode.childNodes,
            numChildNodes = childNodes.length,
            nodeIndex = 0,
            index;

        for (var i = 0; i < numChildNodes; i++) {
            if(childNodes[i].nodeType !== 1) { 
                continue; 
            }

            if(childNodes[i] === clickedListItem) {
                index = nodeIndex;
                break;
            }
            nodeIndex++;
        }

        if(index >= 0) {
            openPhotoSwipe( index, clickedGallery );
        }
        return false;
    };

    var photoswipeParseHash = function() {
        var hash = window.location.hash.substring(1),
        params = {};

        if(hash.length < 5) { // pid=1
            return params;
        }

        var vars = hash.split('&');
        for (var i = 0; i < vars.length; i++) {
            if(!vars[i]) {
                continue;
            }
            var pair = vars[i].split('=');  
            if(pair.length < 2) {
                continue;
            }           
            params[pair[0]] = pair[1];
        }

        if(params.gid) {
            params.gid = parseInt(params.gid, 10);
        }

        return params;
    };

    var openPhotoSwipe = function(index, galleryElement, disableAnimation, fromURL) {
        var pswpElement = document.querySelectorAll('.pswp')[0],
            gallery,
            options,
            items;

        items = parseThumbnailElements(galleryElement);

        // define options (if needed)
        options = {

            galleryUID: galleryElement.getAttribute('data-pswp-uid'),

            getThumbBoundsFn: function(index) {
                // See Options->getThumbBoundsFn section of docs for more info
                var thumbnail = items[index].el.children[0],
                    pageYScroll = window.pageYOffset || document.documentElement.scrollTop,
                    rect = thumbnail.getBoundingClientRect(); 

                return {x:rect.left, y:rect.top + pageYScroll, w:rect.width};
            },

            addCaptionHTMLFn: function(item, captionEl, isFake) {
                if(!item.title) {
                    captionEl.children[0].innerText = '';
                    return false;
                }
                captionEl.children[0].innerHTML = item.title +  '<br/><small>Photo: ' + item.author + '</small>';
                return true;
            }
            
        };


        if(fromURL) {
            if(options.galleryPIDs) {
                // parse real index when custom PIDs are used 
                // http://photoswipe.com/documentation/faq.html#custom-pid-in-url
                for(var j = 0; j < items.length; j++) {
                    if(items[j].pid == index) {
                        options.index = j;
                        break;
                    }
                }
            } else {
                options.index = parseInt(index, 10) - 1;
            }
        } else {
            options.index = parseInt(index, 10);
        }

        // exit if index not found
        if( isNaN(options.index) ) {
            return;
        }



        var radios = document.getElementsByName('gallery-style');
        for (var i = 0, length = radios.length; i < length; i++) {
            if (radios[i].checked) {
                if(radios[i].id == 'radio-all-controls') {

                } else if(radios[i].id == 'radio-minimal-black') {
                    options.mainClass = 'pswp--minimal--dark';
                    options.barsSize = {top:0,bottom:0};
                    options.captionEl = false;
                    options.fullscreenEl = false;
                    options.shareEl = false;
                    options.bgOpacity = 0.85;
                    options.tapToClose = true;
                    options.tapToToggleControls = false;
                }
                break;
            }
        }

        if(disableAnimation) {
            options.showAnimationDuration = 0;
        }

        // Pass data to PhotoSwipe and initialize it
        gallery = new PhotoSwipe( pswpElement, PhotoSwipeUI_Default, items, options);

        // see: http://photoswipe.com/documentation/responsive-images.html
        var realViewportWidth,
            useLargeImages = false,
            firstResize = true,
            imageSrcWillChange;

        gallery.listen('beforeResize', function() {

            var dpiRatio = window.devicePixelRatio ? window.devicePixelRatio : 1;
            dpiRatio = Math.min(dpiRatio, 2.5);
            realViewportWidth = gallery.viewportSize.x * dpiRatio;


            if(realViewportWidth >= 1200 || (!gallery.likelyTouchDevice && realViewportWidth > 800) || screen.width > 1200 ) {
                if(!useLargeImages) {
                    useLargeImages = true;
                    imageSrcWillChange = true;
                }
                
            } else {
                if(useLargeImages) {
                    useLargeImages = false;
                    imageSrcWillChange = true;
                }
            }

            if(imageSrcWillChange && !firstResize) {
                gallery.invalidateCurrItems();
            }

            if(firstResize) {
                firstResize = false;
            }

            imageSrcWillChange = false;

        });

        gallery.listen('gettingData', function(index, item) {
            if( useLargeImages ) {
                item.src = item.o.src;
                item.w = item.o.w;
                item.h = item.o.h;
            } else {
                item.src = item.m.src;
                item.w = item.m.w;
                item.h = item.m.h;
            }
        });

        gallery.init();
    };

    // select all gallery elements
    var galleryElements = document.querySelectorAll( gallerySelector );
    for(var i = 0, l = galleryElements.length; i < l; i++) {
        galleryElements[i].setAttribute('data-pswp-uid', i+1);
        galleryElements[i].onclick = onThumbnailsClick;
    }

    // Parse URL and open gallery if it contains #&pid=3&gid=1
    var hashData = photoswipeParseHash();
    if(hashData.pid && hashData.gid) {
        openPhotoSwipe( hashData.pid,  galleryElements[ hashData.gid - 1 ], true, true );
    }
};

initPhotoSwipeFromDOM('.demo-gallery');

})();